JPH05237406A - Vertical mill - Google Patents

Abstract

PURPOSE:To provide a vertical mill capable of producing a product whose particle size distribution has two peaks. CONSTITUTION:A secondary classifying device 25 guiding a part of the return powder 8' rejected by the primary classifier 23 of a primary classifying device 22 from the under side of the primary classifier 23 through a duct 24 to secondarily classifying the same is provided outside the mill main body equipped with primary classifying device 22 on the upper side of a grinding part 21 having a grinding table 6 and a grinding roller 7 and a particle size control cone 35 for adjusting the particle size of the return powder 8' guided to the inlet part of the duct 24 is provided at the position below the primary classifier 23 in the mill main body 20 in a liftable manner.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a vertical mill.

[0002]

2. Description of the Related Art FIG. 4 shows an example of a general vertical mill, in which a crushed material 3 from a crushed material charging chute 2 inserted in a mill casing 1 is passed through a speed reducer 5 by an electric motor 4. Grinding is performed between the upper surface of the crushing table 6 that is driven to rotate and the crushing roller 7 that rolls following the rotation of the crushing table 6 while being pressed against the upper surface of the crushing table 6 by a pressing device (not shown). The generated powder 8 is blown up by carrier air 10 from a blow-out port 9 provided in an annular shape so as to surround the crushing table 6, and the circumferential direction of a funnel-shaped slit cone 11 that divides the inside of the mill casing 1 into upper and lower parts. The powder 8 is conveyed upward through the openings 13 (see FIG. 5) formed by bulging the outer edge portion 12 at a plurality of locations, and the powder 8 guided further upward is guided to the classifier 14 located in the upper portion inside the mill casing 1. Sizing fine powder delivery pipe 15 connected only fine particles of less than a predetermined particle size into the mill casing 1 top
Through the bag filter 16 to collect the return powder 8'bounced by the classifier 14 by sliding down the inclined surface between the openings 13 of the slit cone 11 to form a drop hole at the lower end of the slit cone 11. It returns from 17 to the central part of the crushing table 6.

In the figure, 18 is a suction fan, and 19 is an electric motor for rotationally driving the classifier 14.

According to the vertical mill as described above, as shown in FIG. 6, particles having a fine particle size distribution having a peak at a predetermined particle size x are obtained as a crushed product.

[0005]

However, in recent years, various powder products such as cement have been required to have a product having a particle size distribution having two peaks. For example, in the case of cement materials, fine particles have a property of rapidly solidifying. Since, since the coarse particles have the property of increasing the strength, a product having a particle size distribution having a peak in each of the fine particle size region and the coarse particle size region is desired,
With the conventional vertical mill, a product having a particle size distribution having such two peaks cannot be obtained.

The present invention has been made in view of the above circumstances, and an object thereof is to provide a vertical mill capable of producing a product having a particle size distribution having two peaks.

[0007]

SUMMARY OF THE INVENTION According to the present invention, a primary classifier of the primary classifier is provided outside a mill body having a primary classifier on the upper side of a crushing section having a crushing table and a crushing roller. Vertical mill characterized by providing a secondary classifier for guiding a part of the returned powder from the lower side of the primary classifier through a duct to perform secondary classification, and the position below the primary classifier in the mill body. In addition, the present invention relates to a vertical mill characterized in that a particle size adjusting cone for adjusting the particle size of the return powder guided to the inlet of the duct is provided so as to be able to move up and down.

[0008]

Therefore, in the present invention, the peak of the particle size distribution of the powder classified and collected by the primary classifier and the peak of the particle size distribution of the powder classified and collected by the secondary classifier are respectively obtained. By setting different particle sizes and mixing the powders that have been classified and collected by the primary classifier and the secondary classifier, a product with a particle size distribution having two different particle sizes as peaks can be obtained. .

Further, if a structure is provided below the primary classifier in the mill body, in which a particle size adjusting cone for adjusting the particle size of the return powder guided to the duct inlet can be raised and lowered, a particle size adjusting cone can be used. By moving up and down to adjust the gap between the lower end of the primary classifier and the upper end of the particle size adjusting cone,
It is possible to adjust the setting of the peak of the particle size distribution of the powder that is classified and collected by the secondary classifier.

[0010]

Embodiments of the present invention will be described below with reference to the drawings.

FIGS. 1 and 2 show an embodiment of the present invention, in which parts designated by the same reference numerals as those in FIGS. 4 and 5 represent the same parts.

Reference numeral 20 in the drawing denotes a mill main body having substantially the same structure as the vertical mill shown in FIGS. 4 and 5 described above.
0 is a crushing unit 2 including a crushing table 6 and a crushing roller 7.
1 and a primary classifier 2 provided above the crushing unit 21
2 and has openings 13 (see FIG. 5) at a plurality of positions in the circumferential direction between the crushing section 21 and the primary classifying device 22 and the lower end is above the center of the crushing table 6. A funnel-shaped slit cone 11 having an opening is provided so as to vertically divide the inside of the mill body 20.

Further, the primary classifying device 22 has a bag filter 16 and a suction fan 1 at the top through a fine powder delivery pipe 15.
8 and a primary casing 23 surrounded by the upper portion of the mill casing 1.

Further, outside the mill main body 20, there is provided a secondary classifying device 25 for guiding a part of the return powder 8'under the primary classifier 23 through a duct 24 to carry out secondary classification. The secondary classifier 25 has a lower part connected to a drop opening 17 at the lower end of the slit cone 11 via a coarse particle return pipe 26 and an upper part connected to a bag filter 28 and a suction fan 29 via a fine powder delivery pipe 27. Secondary classification casing 30
And a secondary classifier 31 surrounded by the secondary classifying casing 30 and a duct 24 that connects the lower side of the primary classifier 23 and the lower side of the secondary classifier 31 described above.

Here, the secondary classifier 25 is installed above the slit cone 11 so that the coarse particles repelled by the secondary classifier 31 can slide down the coarse particle return pipe 26 well by gravity. Further, at the outlet of the coarse particle return pipe 26, a damper 32 that is opened only in the coarse particle discharge direction is provided so that the carrier air 10 is not introduced into the coarse particle return pipe 26.

The powder 8a collected by the bag filter 16 of the primary classifying device 22 is cut out by the feeder 33 and collected by the bag filter 28 of the secondary classifying device 25. The powder 8b is the feeder 3
3 is cut out in the middle of step 3, mixed with the powder 8a, and taken out as a product 34 from the end portion of the feeder 33.

Further, the primary classifier 2 in the mill body 20.
In the lower part of 3, the return powder 8 ′ guided to the inlet of the duct 24
Particle size adjusting cone 35 (see FIG. 2) for adjusting the particle size of
Are suspended and supported by a support 36 from a plurality of circumferential positions (6 positions in the illustrated example) of the top plate of the mill casing 1, and the tightening amount of a nut 37 for fixing each support 36 to the top face of the top plate. The particle size adjusting cone 35 can be moved up and down by adjusting.

The grain size adjusting cone 35 has a notch 38 for avoiding interference with the duct 24 when moving up and down.
Are formed.

Thus, the carrier air 1 from the outlet port 9
The powder 8 blown up from the outer periphery of the crushing table 6 by 0
Is a refined powder which passes through the opening 13 of the slit cone 11 and ascends between the particle size adjusting cone 35 and the mill casing 1 and is classified by the primary classifier 23 so that only fine particles of a predetermined particle size or smaller are connected to the top. Coarse particles of the return powder 8'which are guided and collected by the bag filter 16 through the delivery pipe 15 and cannot pass through the primary classifier 23 are repelled to the mill casing 1 and the mill casing 1 and the particle size adjusting cone. 35, and then slides between the openings 13 of the slit cone 11 and returns to the center of the crushing table 6.

Further, the relatively fine particles of the return powder 8'are guided to the lower side of the primary classifier 23 through the gap between the lower end of the primary classifier 23 and the upper end of the particle size adjusting cone 35 and the duct 24. The secondary classifier 31 is introduced into the secondary classifier 25 through the duct 24 and is guided to the lower side of the secondary classifier 31 of the secondary classifier 25 to be classified by the secondary classifier 31. Only fine particles having a predetermined particle size or less are connected to the top. Bag filter 2 through the fine powder delivery pipe 27
The coarse particles that are guided to 8 and collected and cannot pass through the secondary classifier 31 are repelled to the secondary classifying casing 30, slid down the coarse particle return pipe 26, and returned to the center of the crushing table 6.

The primary classifier 22 and the secondary classifier 2
In order to adjust the setting of the peak of the particle size distribution of the powders 8a and 8b classified and collected by the No. 5, the primary classifier 22
And a suction fan 1 connected to the secondary classification device 25, respectively.
It suffices to adjust the suction force of Nos. 8 and 29, and in particular, the peak of the particle size distribution of the powder 8b that is classified and collected by the secondary classifier 25 is set up by moving the particle size adjusting cone 35 up and down the primary classifier 23 By adjusting the gap between the lower end and the upper end of the grain size adjusting cone 35, more accurate adjustment can be performed.

By adjusting the rotation speeds of the primary classifier 23 and the secondary classifier 31, each bag filter 1
It is possible to specify the maximum particle diameter of the powder 8 collected in Nos. 6 and 18.

Therefore, according to the above embodiment, the powder 8 classified and collected by the primary classifier 22 is set to have a particle size distribution having a peak of a predetermined particle size x as shown by A in FIG. The powder 8 classified and collected by the secondary classifier 25 is set to have a particle size distribution having a peak of a particle size y larger than the particle size x as shown by B in FIG. If the powder 8 of each bag filter 16 and 28 connected to the next classifier 25 is mixed on the feeder 33,
It is possible to obtain a product 34 having a particle size distribution having peaks of the particle size x and the particle size y, respectively.

Further, since the particles having a particle size which can be the product 34 are recovered from the return powder 8'repelled by the primary classifier 23 by the duct 24 and secondary classified.
In the case of the conventional vertical mill, the particles in the coarse area where the particles are returned to the crushing table 6 and re-crushed by the classifier are promptly recovered from the inside of the mill body 20, and the crushing unit 21 is used. The pulverization efficiency of can be significantly improved.

By moving the particle size adjusting cone 35 up and down to adjust the gap between the lower end of the primary classifier 23 and the upper end of the particle size adjusting cone 35, the powder classified and collected by the secondary classifying device 25 is collected. The setting of the peak of the particle size distribution of the body 8b can be adjusted extremely easily and accurately.

The vertical mill of the present invention is not limited to the above-mentioned embodiment, and it goes without saying that various modifications can be made without departing from the gist of the present invention.

[0027]

According to the vertical mill of the present invention described above, various excellent effects as described below can be obtained.

(I) A product having a particle size distribution having two peaks can be produced.

(II) Among the return powders repelled by the primary classifier, particles having a particle size that can be used as a product are returned to the crushing table and collected in the duct without being crushed again for secondary classification. In the case of a conventional vertical mill, particles in a coarse particle area, which had been returned to the crushing table by a classifier and crushed again, will be promptly recovered from the inside of the mill body. The efficiency can be significantly improved.

(III) If a structure in which a particle size adjusting cone for adjusting the particle size of the return powder introduced to the duct inlet is provided up and down at the position below the primary classifier in the mill body, the particle size adjustment can be performed. By raising and lowering the cone and adjusting the gap between the lower end of the primary classifier and the upper end of the particle size adjusting cone, it is extremely easy to set the peak of the particle size distribution of the powder that is classified and collected by the secondary classifier. In addition, it can be adjusted with high accuracy.

[Brief description of drawings]

FIG. 1 is a sectional view showing an embodiment of the present invention.

2 is a perspective view of the grain size adjusting cone of FIG. 1. FIG.

FIG. 3 is a graph showing a particle size distribution of each powder classified and collected by the primary classifier and the secondary classifier in one example of the present invention.

FIG. 4 is a cross-sectional view showing a conventional example.

5 is a view in the direction of VV in FIG.

FIG. 6 is a graph showing a particle size distribution of powder that is classified and collected by a classifier in a conventional example.

[Explanation of symbols]

 6 Grinding table 7 Grinding roller 8'Return powder 20 Mill body 21 Grinding section 22 Primary classifier 23 Primary classifier 24 Duct 25 Secondary classifier 35 Particle size adjusting cone

Claims (2)

[Claims] 1. Outside a mill body equipped with a primary classifying device above a crushing section having a crushing table and a crushing roller,
A vertical mill provided with a secondary classifier for guiding a part of the return powder repelled by the primary classifier of the primary classifier from a lower side of the primary classifier through a duct to perform secondary classification. 2. At the position below the primary classifier in the mill body,
The vertical mill according to claim 1, wherein a particle size adjusting cone for adjusting the particle size of the return powder guided to the inlet of the duct is provided so as to be able to move up and down.